Liquid-attenuated exhaust system

ABSTRACT

Apparatus and method for injecting droplets of a liquid such as water into the exhaust pipe of an internal combustion engine, passing the mixture of exhaust gases and liquid droplets through a muffler, removing the liquid from the exhaust gases and cooling and recirculating the liquid. The liquid droplets mixed with the exhaust gases greatly decreases the exhaust noise, cool the exhaust gases, and remove substantial quantities of solid particles.

United States Patent [72] Inventor Wayne M. Wagner Rosemount, Minn. [21] Appl. No. 9,536 [22] Filed Feb. 9, 1970 [45] Patented Dec. 28, 1971 [73] Assignee Donaldson Company, Inc.

Minneapolis, Minn.

[54] LlQUlD-ATTENUATED EXHAUST SYSTEM 6 Claims, 7 Drawing Figs.

[52] US. Cl 60/274, 55/89, 55/228, 55/229, 55/257, 181/52, 60/310 [51] Int. Cl F0ln 3/04 [50] Field of Search ..60/29, 30 L, 31; 55/89, 95, 228, 229, 257, DIG. 30; 181/52 [56] References Cited UNITED STATES PATENTS 1,142,073 6/1915 Wolff 60/30L 2,768,705 l0/1956 lsserlis 55/DlG. 30

MUFFLER INTERNRL COHBUST ION ENGINE I2.

Primary Examiner- Douglas Hart Anorney-Merchant & Gould ABSTRACT: Apparatus and method for injecting droplets of a liquid such as water into the exhaust pipe of an internal combustion engine, passing the mixture of exhaust gases and liquid droplets through a muffler, removing the liquid from the exhaust gases and cooling and recirculating the liquidv The liquid droplets mixed with the exhaust gases greatly decreases the exhaust noise, cool the exhaust gases, and remove substantial quantities of solid particles.

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LIQUID-ATTENUATED EXHAUST SYSTEM BACKGROUND OF THE INVENTION 1. Field of the Invention The exhaust from combustion engines is the outlet for most of the noise produced by these engines as well as the exhaust gases and other products of combustion. With the number of combustion engines being operated daily, the noise produced thereby is becoming a substantial nuisance. Further, the exhaust gases and combustion byproducts are beginning to seriously pollute the air so that steps are being taken to utilize different types of engines as power sources in some instances.

2. Description of the Prior Art In the prior art a variety of different types of apparatus are disclosed for quenching inflammable particles in exhaust gases or for cleaning certain waste products from the exhaust gases. An example of the former device is U.S. Pat. No. 2,763,982, issued to R.L. Dega on Sept. 25, 1965 titled Centrifugal Apparatusfor Treating Exhaust Gas." Dega discloses spraying water of other suitable liquids into the exhaust conduit leading from an engine to quench inflammable particles in the exhaust gas. Very shortly after spraying the water into the exhaust conduit the water is removed from the exhaust conduit by means of a centrifugal separator. The water is simply maintained in the exhaust long enough to wet or quench inflammable particles and the water and inflammable particles are then immediately removed.

An example of the later type of device is disclosed in U.S. Pat. No. 3,282,047, issued to S. B. Wertheimer on Nov. 1, 1966 and entitled Purifying Apparatus to Eliminate Air Pollution from Automotive, Industrial, and Commercial Exhaust Products. In this structure the exhaust gases simply pass through a chamber wherein a purifying liquid is formed into a curtainlike mist by spraying downwardly. The curtain of spray purifies the exhaust gases by removing all soluble gases therefrom and some of the solid particles. In this device the spray is moving perpendicular to the direction of movement of the exhaust gases and operates similar to a filter to remove the various particles.

SUMMARY OF THE INVENTION The present invention pertains to an improved liquid-attenuated exhaust system for a combustion engine including means for injecting a relatively continuous flow of droplets of liquid into the exhaust gas stream for colling the gases and reducing the exhaust noises, and a muffler affixed to the exhaust conduit downstream from the liquid-injecting means.

It is an object of the present invention to provide an improved liquid'attenuated exhaust system for combustion engines.

It is a further object of the present invention to provide an improved liquid-attenuated exhaust system wherein exhaust noises are substantially attenuated.

It is a further object of the present invention to provide an improved liquidattenuated exhaust system which substantially cools the exhaust gases and removes at least some of the solid materials therein.

It is a further object of the present invention to provide an improved liquid-attenuated exhaust system which decreases the wavelengths of the exhaust noise components and provides sufficient absorptive effect so that a muffler downstream from the fluid-injecting means can more effectively reduce the exhaust noises for a given size muffler.

These and other objects of this invention will become apparent to those skilled in the art upon consideration of the accompanying specification, claims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Referring to the drawings, wherein like characteristics indicate like parts throughout the figures:

FIG. I is a somewhat schematic view of an embodiment of the improved exhaust system operatively attached to the exhaust of a combustion engine;

FIG. 2 is an enlarged fragmentary view of the injecting means utilized in the embodiment of FIG. 1, portions thereof broken away and shown in section;

FIG. 3 is a somewhat schematic view of another embodiment of the improved exhaust system operatively attached to the exhaust of a combustion engine;

FIG. 4 is an enlarged fragmentary axial sectional view of the injecting means utilized in the exhaust system of FIG. 3;

FIG. 5 is a somewhat schematic view of another embodiment of the improved exhaust system operatively attached to the exhaust of a combustion engine;

FIG. 6 is another embodiment of the improved exhaust system operatively attached to the exhaust of a combustion engine; and

FIG. 7 is another embodiment of the improved exhaust system operatively attached to the exhaust of a combustion engine.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, a combustion engine generally designated 10 is illustrated in block form, since the specific,

construction of the engine 10 does not form a part of this invention. The products of combustion, including hot gases, solids, and the like, are exhausted from the combustion engine 10 through an exhaust port 11. An exhaust conduit I2 connected in communication with the exhaust port 11 terminates at an inlet ofa muffler l3 and a second length of exhaust conduit 14 extends from an outlet of the muffler 13 to an inlet 19 of a special radiator generally designated 20. The radiator 20 has a lower fluid-filled portion 21 having a core 22 therein for cooling the fluid in the usual manner. A fan 23 is illustrated for forcing air over the core 22 to cool the fluid in the radiator 20 and maintain thermal equilibrium, however. If the combustion engine 10 is utilized to drive a vehicle the radiator 20 may be cooled by the normal passage of air therethrough. An upper portion of the radiator 20 forms a tank 25 into which the exhaust gases from the inlet 19 are forced. The tank 25 has a plurality of baffles 26 therein and an exhaust outlet 27.

A fluid conduit 30 communicates with the fluid-filled portion 21 of the radiator 20 and a fluid pump 31. Fluid under pressure is forced by the pump 31 through a fluid conduit 32, having a valve 33 therein, to a fluid-injecting means 34-positioned in the exhaust conduit 12. In this embodiment, the fluid-injecting means 34 is a nozzle (illustrated in detail in FIG. 2) which sprays a relatively continuous flow of droplets of fluid into the exhaust conduit 12. The valve 33 is supplied to manually or automatically supply pressurized fluid to the injecting means 30 whenever the engine 10 is operating. The pump 31 may be operated by separate means or may be rotated by the engine 10.

In the operation of the embodiment illustrated in FIGS. I and 2, exhaust gases egress from the engine 10 through he exhaust port 11 and follow the exhaust conduit 12 to the injecting means 34. At the injecting means 34 droplets of fluid are injected and dispersed throughout the exhaust gases in a substantially continuous flow and the mixture of exhaust gases and droplets of liquid pass through the muffler l3 and exhaust conduit 14 to the tank 25. In the tank 25 the baffles 26 slow the exhaust gases sufficiently to allow the moisture to precipitate from the exhaust gases and enter the fluid-filled portion 21 of the radiator 20. In the radiator 20 the fluid is cooled by the action of the core 22 and recirculated by the "pump 31.

One of the primary purposes of the present apparatus is to provide attenuation of the exhaust noises. Through substantial experimentation it has been found that injecting droplets of liquid into the exhaust system and mixing them with the exhaust gases aids in providing this function in at least three ways.

1. The liquid cools the exhaust gases to a temperature near ambient, causing the wavelengths of the sound to decrease in length.

where k wavelength (feet) c= velocity of sound (ft./sec.)

f= frequency (c.p.s.)

An engine operating at a given speed produces a fundamental frequency. If the temperature is lowered the speed of sound decreases. This causes the wavelength to decrease by definition since the frequency produced by the engines operating speed and firing frequency.

c=l052+l.l06 F. ft./sec. where F. temp. in Farenheit degrees. Typical wavelengths for exhaust gas at 100 c.p.s. would be about 20 feet, requiring -foot long muffler chambers (onefourth wavelength) to attenuate the sound. Cooling the exhaust gas to ambient reduces the wavelength to about l0 feet, requiring Zh-foot long chambers, and in effect making the muffler more effective for low frequencies.

2. The mass of water distributed in droplet form throughout the exhaust system gives an absorptive effect on the highfrequency noise.

3. The cooling of the exhaust gases decrease their speed and exit velocity from the end of the exhaust system to atmosphere, reducing the regenerated sound, or sound which is caused by a high-velocity gas exiting to atmosphere. The velocity decreases directly proportional to the absolute temperature of the gas.

It should be understood that other advantages and/or effects may be produced by the present apparatus but it is believed that the above three are the most important. The experimentation further indicates that approximately 0.005 hp. in. g.p.m. (the gallons per minute injected into the exhaust system equal 0.005 times the horsepower of the engine times the area of the exhaust pipe in square inches) provides a good balance between noise attenuation and back pressure of the exhaust system. It was found that less than half of this flow rate does not provide maximum attenuation and a substantially greater flow rate causes excessive back pressure, with diminishing increases of attenuation.

It should be noted that the system illustrated in FIG. 1 has an exhaust 27 from the tank 20 with a substantially larger cross-sectional area than the cross-sectional area of the exhaust conduits I2 and 14. The speed of the exhaust gases and droplets of liquid through the muffler 13 is substantially undiminished so that very little or no separation of the droplets and exhaust gases occurs therein. In some instances, especially when the engine is running at very low or idling speeds, some separation may occur in the muffler 13 and, consequently, it may be advantageous to include a conduit for draining liquid from the muffler 13 into the fluid-filled portion 2I of the radiator 20. When the mixture of exhaust gases and droplets of liquid enters the tank 25, the substantially increased area reduces the speed or velocity of the gases, thereby, allowing the droplets of moisture to collect on the baffles 26 or precipitate from the exhaust gases. The increased cross-sectional area of the exhaust 27 allows this conduit to operate in a fashion similar to a vent, rather than a pressurized exhaust.

FIGS. 3 and 4 illustrate a second embodiment of the improved liquid-attenuated exhaust system wherein a combustion engine 10 has an exhaust port 11a with an exhaust conduit 12a in communication therewith. The exhaust conduit 12a is further in communication with the inlet of a muffler 13a, the outlet of which is connected through an exhaust conduit 14a to a separator 40. The separator 40 may be any convenient separator, such as a centrifugal separator or the like, for separating the droplets of liquid from the exhaust gases, wherein the exhaust gases egress through an exhaust 41 to the atmosphere and the liquid passes through a conduit 42 into a heat exchanger 43. The heat exchanger 43 serves as a source of cool liquid, which is supplied through a conduit 44 and valve 45 to an injecting means 46. In this embodiment the injecting means 46 is a venturi device which draws the liquid from the conduit 44 and mixes it with the exhaust gases so that no pump is required. It should be understood that the separator and heat exchanger 43 might be eliminated and the radiator 20 of the first embodiment utilized in lieu thereof, or vice versa. This embodiment might be utilized for stationary installations where a radiator and air normally passing therethrough is not available.

Referring to FIG. 5, a third embodiment of the improved liquid-attenuated exhaust system is illustrated wherein a combustion engine 10b having an exhaust port Ilb is connected through an exhaust conduit ll2b to a muffler 13b and the muffler 13b is connected through an exhaust conduit 14b to a separator 40b. The exhaust gases egress from the separator 40b through an exhaust 41b and the separated liquid passes through a conduit 42b to a heat exchanger 43b, which in this case is a radiator or radiator and fan 23b. If this particular embodiment is utilized in vehicles the radiator may not require the fan 23b for cooling purposes. The heat exchanger or radiator 43b delivers the fluid through a fluid conduit 30b, pump 31b, conduit 32b and valve 33b to an injecting means 34b. Since a pump 31b is included in this embodiment it is anticipated that the injecting means 34b will be similar to that illustrated in FIG. 2, however, it should be understood that the pump 31b might be eliminated and the injecting means 34b might be similar to that illustrated in FIG. 4, if desired. A liquid tank 50 is connected to the fluid conduit 30b through a conduit 51 and serves to replenish liquid which is lost through the exhaust 41b due to saturation of the exhaust gas (not boiling to steam) and maintains the liquid in the system at the correct level.

FIG. 6 illustrates a fourth embodiment of the improved liquid-attenuated exhaust system similar to the embodiment illustrated in FIG. 3, except that the injecting means 340 is similar to the injecting means illustrated in FIG. 2 and a pump 310 is provided in the system to supply liquid under pressure thereto. This particular embodiment, as described in conjunction with FIG. 3, is for use with stationary installations where a constant flow of air and radiator are not readily available.

A fifth embodiment of the improved liquid-attenuated exhaust system is illustrated in FIG. 7, which embodiment is similar to that illustrated in FIG. 6, except that the heat exchanger 430 is eliminated and a cooling tower 43d is substituted therefor. This particular embodiment is adapted for use in large generating plants and the like wherein a cooling tower can be readily positioned external of the enclosure. The cooling tower 43d provides the same function as the radiator 43b in the embodiment of FIG. 5 and the heat exchanger 43c in the embodiment of FIG. 6. In the embodiment illustrated in FIG. 7 the liquid utilized will generally be water and it is a simple matter to replenish the water lost from the cooling tower by evaporation and the water lost through the exhaust 410. A simple float valve (not illustrated) can be attached to a water conduit which is in communication with the city water supply or other water supply to maintain the level of water within the cooling tower 4311 at a required height.

In all of the embodiments illustrated the liquid utilized may be simply water, since this is generally the most inexpensive and readily available liquid, but in some special instances additives or other liquids may be required. For example, in vehicles utilized during the winter months in the colder countries or portions thereof there will be a danger of pure water freezing in the system, when not in use. In these instances it may be necessary to introduce at least some antifreeze into the liquid. Other additives acting as catalysts may be used for reducing pollutants.

Thus, an improved liquid-attenuated exhaust system for combustion engines is described wherein the exhaust noises are substantially reduced and products of combustion, such as solid particles and the like egressing through the exhaust system are substantially removed. In addition, the exhaust gases are greatly cooled so that fire hazards and the like are eliminated.

What is claimed is:

l. A sound-attenuation system for a combustion engine having an exhaust outlet through which a high-velocity stream of exhaust gases is discharged, comprising:

a. an exhaust conduit affixed to said exhaust outlet;

b. a normally dry muffler having an inlet conduit and an outlet conduit, said inlet conduit being affixed to said exhaust conduit;

c. a source of liquid;

d. means communicating with said source of liquid and said exhaust conduit for injecting, during operation of said engine, a continuous flow of droplets of liquid directly into the high-velocity exhaust stream in quantities substantially larger than needed to saturate the exhaust gases;

. separating means communicating with said outlet conduit of said muffler for removing excess liquid from the exhaust gases;

. liquid conduit means connected to said separating means and to the liquid source for recirculating the separated liquid; and

g. heat-exchanging means in communication with said liquid conduit means for cooling the separated liquid prior to recirculation thereof to maintain thermal equilibrium.

2. An improved liquid-attenuated exhaust system as set forth in claim 1, wherein the heat-exchanging means includes a radiator on a vehicle powered by the combustion engine.

3. An improved liquid-attenuated exhaust system as set forth in claim 1, wherein the gallons per minute injected by the injecting means is approximately equal to the product of the horsepower of the engine and the square inches of the exhaust outlet area of the engine times 0.005.

4. A method of reducing the noise in the exhaust of a combustion engine comprising the steps of continuously injecting droplets of liquid directly into the high-velocity stream of exhaust gases being discharged by the engine in substantially larger quantities than needed to saturate the gases, passing the resulting homogeneous mixture of exhaust gases and liquid through a muffler at a substantially undiminished velocity so that very little separation of the droplets and exhaust gases occur therein, separating the excess liquid from the exhaust gases after passage through the muffler, and recirculating the separated liquid.

5. A method of reducing the noise in the exhaust of a combustion engine as set forth in claim 4 including in addition the step of cooling the separated liquid prior to reinjecting it into the exhaust to maintain thermal equilibrium.

6. A method of reducing the noise in the exhaust of a combustion engine as set forth in claim 4, wherein the flow rate of liquid injected is approximately 0.005 times the product of the horsepower of the engine and the square inches of the exhaust pipe area of the engine. 

1. A sound-attenuation system for a combustion engine having an exhaust outlet through which a high-velocity stream of exhaust gases is discharged, comprising: a. an exhaust conduit affixed to said exhaust outlet; b. a normally dry muffler having an inlet conduit and an outlet conduit, said inlet conduit being affixed to said exhaust conduit; c. a source of liquid; d. means communicating with said source of liquid and said exhaust conduit for injecting, during operation of said engine, a continuous flow of droplets of liquid directly into the highvelocity exhaust stream in quantities substantially larger than needed to saturate the exhaust gases; e. separating means communicating with said outlet conduit of said muffler for removing excess liquid from the exhaust gases; f. liquid conduit means connected to said separating means and to the liquid source for recirculating the separated liquid; and g. heat-exchanging means in communication with said liquid conduit means for cooling the separated liquid prior to recirculation thereof to maintain thermal equilibrium.
 2. An improved liquid-attenuated exhaust system as set forth in claim 1, wherein the heat-exchanging means includes a radiator on a vehicle powered by the combustion engine.
 3. An improved liquid-attenuated exhaust system as set forth in claim 1, wherein the gallons per minute injected by the injecting means is approximately equal to the product of the horsepower of the engine and the square inches of the exhaust outlet area of the engine times 0.005.
 4. A method of reducing the noise in the exhaust of a combustion engine comprising the steps of continuously injecting droplets of liquid directly into the high-velocity stream of exhaust gases being discharged by the engine in substantially larger quantities than needed to saturate the gases, passing the resulting homogeneous mixture of exhaust gases and liquid through a muffler at a substantially undiminished velocity so that very little separation of the droplets and exhaust gases occur therein, separating the excess liquid from the exhaust gases after passage through the muffler, and recirculating the separated liquid.
 5. A methOd of reducing the noise in the exhaust of a combustion engine as set forth in claim 4 including in addition the step of cooling the separated liquid prior to reinjecting it into the exhaust to maintain thermal equilibrium.
 6. A method of reducing the noise in the exhaust of a combustion engine as set forth in claim 4, wherein the flow rate of liquid injected is approximately 0.005 times the product of the horsepower of the engine and the square inches of the exhaust pipe area of the engine. 